Born at 24 weeks by emergency C-section in August last year, when he weighed just 268g (9.45oz), the smallest boy in the world to have been successfully treated was released last week from the hospital in Japan.

His name has not been released by hospital. The C-section was performed as a hope to help him after he failed to gain weight during the pregnancy and doctors feared his life was in danger. Doctor Takeshi Arimitsu treated him. The boy had grown to a weight of 3.2kg and is now feeding normally. "I can only say I'm happy that he has grown this big because honestly, I wasn't sure he could survive," the boy's mother said. Having him in life was a medical performance. Doctors are proud to have such results.

Image: Keio University Hospital

Keio University Hospital said the survival rate of babies born weighing less than a kilogram is about 90% in Japan. However for those born under 300g, that falls to around 50%. The previous record-holder was a boy born in Germany, weighing 274g. The smallest surviving baby girl in that same database was also born in Germany, in 2015, and reportedly weighed 252g.